Aperiodic MEG abnormality in patients with focal to bilateral tonic-clonic seizures

Aperiodic activity is a physiologically distinct component of the electrophysiological power spectrum. It is suggested to reflect the balance of excitation and inhibition in the brain, within selected frequency bands. However, the impact of recurrent seizures on aperiodic activity remains unknown, particularly in patients with severe bilateral seizures. Here, we hypothesised greater aperiodic abnormality in the epileptogenic zone, in patients with focal to bilateral tonic clonic (FBTC) seizures, and earlier age of seizure onset. Pre-operative magnetoencephalography (MEG) recordings were acquired from 36 patients who achieved complete seizure freedom (Engel I outcome) post-surgical resection. A normative whole brain map of the aperiodic exponent was computed by averaging across subjects for each region in the hemisphere contralateral to the side of resection. Selected regions of interest were then tested for abnormality using deviations from the normative map in terms of z-scores. Resection masks drawn from postoperative structural imaging were used as an approximation of the epileptogenic zone. Patients with FBTC seizures had greater abnormality compared to patients with focal onset seizures alone in the resection volume (p=0.003, area under the ROC curve = 0.78 ). Earlier age of seizure onset was correlated with greater abnormality of the aperiodic exponent in the resection volume (correlation coefficient = -0.3, p= 0.04)) as well as the whole cortex (rho = -0.33, p=0.03). The abnormality of the aperiodic exponent did not significantly differ between the resected and non-resected regions of the brain. Abnormalities in aperiodic components relate to important clinical characteristics such as severity and age of seizure onset. This suggests the potential use of the aperiodic band power component as a marker for severity of epilepsy

Controversies in neurosurgery: Irreducible basilar invagination and atlanto-axial dislocation: A trans-oral procedure may be avoided in a majority, but still may be required in some cases

Basilar invagination (BI) and atlanto-axial dislocation (AAD) are mostly irreducible in nature and are quite complex pathologies to manage. Traditionally they required a trans-oral excision of odontoid process followed by a posterior instrumented fusion. This has been challenged recently, where a single staged posterior only procedure addresses both reduction and decompression in the same sitting. This evidence was based on earlier publication and also on the author′s own experience, where he described a new technique (distraction, compression, extension and reduction), which performed for the 1 st time a 2-axis movement in the cranio-vertebral junction (CVJ) allowing effective reduction of both AAD and BI. This technique has now become a standard in the author′s armentorium for management of CVJ anomalies and allowed a single stage posterior only surgery for 95% of these pathologies managed by him. Although this technique could address a majority of cases of developmental BI and AAD, it becomes important to understand that a trans-oral excision of dens followed by a posterior instrumented fusion will still be required in some cases. These include certain cases of clival segmentation anomalies, very severe BI, infective pathologies like tuberculosis with circumferential compression and bony destruction and tumors. The following review article is based on the author′s personal experience of over 500 cases and discusses the advantages and limitations of single staged surgery and the indications of trans-oral surgery in this rapidly evolving field

Understanding complexities of synaptic transmission in medically intractable seizures: A paradigm of epilepsy research

Investigating the changes associated with the development of epileptic state in humans is complex and requires a multidisciplinary approach. Understanding the intricacies of medically intractable epilepsy still remains a challenge for neurosurgeons across the world. A significant number of patients who has undergone resective brain surgery for epilepsy still continue to have seizures. The reason behind this therapy resistance still eludes us. Thus to develop a cure for the difficult to treat epilepsy, we need to comprehensively study epileptogenesis. Although various animal models are developed but none of them replicate the pathological conditions in humans. So the ideal way to understand epileptogenecity is to examine the tissue resected for the treatment of intractable epilepsy. Advanced imaging and electrical localization procedures are utilized to establish the epileptogenic zone in epilepsy patients. Further molecular and cytological studies are required for the microscopic analysis of brain samples collected from the epileptogenic focus. As alterations in inhibitory as well as excitatory synaptic transmission are key features of epilepsy, understanding the regulation of neurotransmission in the resected surgery zone is of immense importance. Here we summarize various modalities of in vitro slice analysis from the resected brain specimen to understand the changes in GABAergic and glutamatergic synaptic transmission in epileptogenic zone. We also review evidence pertaining to the proposed role of nicotinic receptors in abnormal synaptic transmission which is one of the major causes of epileptiform activity. Elucidation of current concepts in regulation of synaptic transmission will help develop therapies for epilepsy cases that cannot me managed pharmacologically

Legal sanctity of consent for surgical procedures in India

As surgeons, we are morally committed to respecting the right of self-determination of patients, thus an informed consent is necessary before any operative intervention. Many neurosurgical patients are incapable of giving consent because of impaired consciousness. Moreover, neurosurgical procedures involve high risks and often are time sensitive; therefore obtaining consent is a challenging job. Patients and their family members need immense courage, understanding, and trust before giving consent for a surgical procedure to a doctor. Lawsuits against doctors are on the rise and it is important to understand "what is consent?" in legal parlance